* fix dataloader collate return list mix tensor and numpy array. test=develop

* remove numpy array check in single-process dataloader. test=develop

* fix failed tests in yingchun gived list

* add unittests into static_mode_white_list

* add enable static

* fix dist unittest

* skip test_sigmoid_focal_loss_op & add gym

* revert no need skip unittests

* remove gym

* add paddle.io.ComposeDataset & paddle.io.ChainDataset. test=develop

* add TensorDataset. test=develop